Oxidation in a circular trench is of relevance in several applications, including trench capacitors in memories. In this work a model for stress-dependent oxidation is presented. The model is based on modifications of the Deal-Grove model, which is used conventionally for planar oxidation. It is seen that even when stress-effects are ignored, the circular tranch geometry leads to a drop in the oxidation rate, in comparison to planar oxidation. The oxidation rate drops even further as the initial diameter of the trench is reduced. When the stress due to volume-expansion is included, with silicon dioxide considered as an elastic material, an additional drop is seen in the oxidation rate. Calibration of the model to measured data involves only a few parameters. Experimental data are presented that qualitatively demonstreate some predictions of the theory.